Carrier 50TC-D25 - Humidi-MiZer Troubleshooting

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Table 4 – Humidi−MiZerR Troubleshooting
PROBLEM CAUSE REMEDY
Subcooling Reheat Mode Will
Not Activate
General cooling mode problem See Cooling Service Troubleshooting (Table 4).
No dehumidification demand See No Dehumidification Demand, below.
CRC relay operation See CRC Relay Operation, below.
Circuit RLV, CLV or LDV valve problem See CLV, RLV or LDV Valve Operation, below.
Hot Gas Reheat Mode Will Not
Activate
General cooling mode problem See Cooling Service Troubleshooting (Table 4).
No dehumidification demand See No Dehumidification Demand, below.
CRC relay operation See CRC Relay Operation, below.
Circuit RLV, CLV or LDV valve problem See CLV, RLV or LDV Valve Operation, below.
Circuit RDV valve is not open See RDV Valve Operation, below.
Outdoor temperature too low
Check Reheat 2 Circuit Limit Temperatures (Configuration → HMZR
→ RA.LO and RB.LO) using ComfortLink Scrolling Marquee.
No Dehumidification Demand
Relative humidity setpoint too low — Humidistat Check/reduce setting on accessory humidistat.
Relative humidity setpoint too low — RH sensor
Check Space RH Setpoints (Setpoints → RH.SP and RH.UN) and
occupancy using ComfortLink Scrolling Marquee.
Software configuration error for accessory
humidistat
Check Space Humidity Switch (Configuration UNIT RH.SW) using
ComfortLink Scrolling Marquee.
Software configuration error for accessory
humidity sensor
Check RH Sensor on OAQ Input (Configuration → UNIT → RH.S)
using ComfortLink Scrolling Marquee.
No humidity signal Check wiring. Check humidistat or humidity sensor.
CRC Relay Operation
No 24V signal to input terminals
Check using Cool→Reheat1 Valve Test (Service Test → HMZR →
CRC) using ComfortLink Scrolling Marquee.
Check MBB relay output.
Check wiring.
Check transformer and circuit breaker.
No power to output terminals Check wiring.
Relay outputs do not change state Replace faulty relay.
RLV, CLV or LDV Valve Operation
No 24V signal to input terminals
Check using Cool→Reheat1 Valve Test (Service Test → HMZR →
CRC) using ComfortLink Scrolling Marquee.
Check CRC Relay Operation.
Check Wiring.
Check transformer and circuit beaker or fuses.
Solenoid coil burnout
Check continuous over-voltage is less than 10%.
Check under-voltage is less than 15%.
Check for missing coil assembly parts.
Check for damaged valve enclosing tube.
Stuck valve Replace valve. Replace filter drier.
RDV Valve Operation
(NOTE: Normally Closed When
De-energized)
No 24V signal to input terminals
Check using Cool→Reheat1 Valve Test (Service Test → HMZR →
RHV.A or RHV.B) using ComfortLink Scrolling Marquee.
Check MBB relay output.
Check wiring.
Check transformer and circuit breaker or fuses.
Solenoid coil burnout
Check continuous over-voltage is less than 10%.
Check under-voltage is less than 15%.
Check for missing coil assembly parts.
Check for damaged valve enclosing tube.
Stuck valve Replace valve. Replace filter drier.
Low Latent Capacity in Subcool
ing or Hot Gas Reheat Modes
CLV valve open or leaking See CLV Valve Operation, above.
Low Sensible Capacity in Normal
Cool or Subcooling Reheat
Modes
RDV valve open or leaking See RDV Valve Operation, above.
Low Suction Pressure and High
Superheat During Normal Cool
Mode
General cooling mode problem See Cooling Service Troubleshooting (Table 4).
RDV valve open or leaking See RDV Valve Operation, above.
Low Suction Pressure and High
Discharge Pressure
General cooling mode problem See Cooling Service Troubleshooting (Table 4).
Both RLV and CLV valves closed See RLV and CLV Valve Operation, above.
RDV Valve Cycling On/Off Hot Gas Reheat mode low suction pressure limit
Normal Operation During Mixed Circuit Subcooling and Hot Gas
Reheat ModesatLowerOutdoorTemperatures.
Circuit B Will Not Operate With
Circuit A Off
Normal operation. Motormaster outdoor fan
control requires operation of circuit A.
None
LEGEND
CRC — Cooling/Reheat Control
CLV — Cooling Liquid Valve
RLV — Reheat Liquid Valve
RH — Relative Humidity
RDV — Reheat Discharge Valve